guest ::
| Home > Publications database > Regional reutilization of thymidine in the normal mouse |
| Home > Publications database > Regional reutilization of thymidine in the normal mouse |
| Book/Report | FZJ-2017-04468 |
; ; ;
1970
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/14834
Report No.: Juel-0649-ME
Abstract: Swiss Albino mice of Yale strain were DNA pulselabeled by i.v. injection, either with H$^{3}$-thymidine (H$^{3}$-TdR) or with 5-iodo$^{125(131)}$-deoxyuridine (IUdR). The distribution of iodine from IUdR between DNA, RNA, protein, lipids and acid-soluble fraction at day 1 and 2 after labeling, and the turnover rates of iodine and tritium from day 1 to day 8 were determined in 14 typesof tissues. Approximately 5 % of the iodine injected with IUdR was retained in the whole body at 24 hours. On the contrary, 50 % of H$^{3}$-TdR is incorporated. More than 90 % of the IUdR was bound to tissue with rapid cell renewal, such as bone marrow and intestinal tract. The amount of iodine recovered with other fractions than DNA was low and, with exception of lymph nodes, stomach, skin and brain, was comparable in all tissues irrespective of the labeling intensity of DNA. At average 0.0075 % of the tracer injected resided in the acid-soluble fraction per gram tissue at 24 hours. At 48 hours it was 0.0067 %. The turnover rate of incorporated IUdR exceeded that measured with H3-TdR in bone marrow, thymus, intestinal tract, spleen and skin, whereas no significant differencewas found in lymph node and liver. More iodine than tritium was retained in tissue with a low degree of cell renewal: lungs, kidneys, heart, skeletal muscle and brain. The latter finding expresses non-specific binding of iodine. The difference between the two turnover rates in conjunctionwith the distribution pattern of IUdR per tissue, allowed quantitatively assessing reutilization of free TdR for tissues with rapid cell proliferation. This analysis is based on the inefficiency of IUdR reutilization compared with TdR.Reutilization of free TdR registered highest inthymus, where it reached 60 %; but none was seen inlymph nodes. The respective value for bone marrow was40 %. In intestinal tract, spleen and skin reutilizationamounted to approximately 30 - 40 %. No significantassessment could be made in tissue with a low degree ofcell renewal.The unequal correlations of turnover rates of thetwo tracers in the various organs indicate the involvementof salvage pathways localized to sites of free TdR availability either from DNA break-down subsequent to celldeath and/or from cell migration.The present data in the context of the high specificity of TdR as DNA precursor requests further evaluationof the physiological role of the free thymidine salvagepathway. Attention is drawn to the parallel renewal rateof iodine and tritium in the mesenteric lymph node, knownto comprise rapidly proliferating cell populations. Thismay signal a salvage pathway different from that involvingfree thymidine.
|
The record appears in these collections: |
PDF
PDF (PDFA)